Question: What do the following two equations represent? $5x+3y = -4$ $-15x+25y = 1$
Explanation: Putting the first equation in $y = mx + b$ form gives: $5x+3y = -4$ $3y = -5x-4$ $y = -\dfrac{5}{3}x - \dfrac{4}{3}$ Putting the second equation in $y = mx + b$ form gives: $-15x+25y = 1$ $25y = 15x+1$ $y = \dfrac{3}{5}x + \dfrac{1}{25}$ The slopes are negative inverses of each other, so the lines are perpendicular.